In an image recording apparatus for recording a medical image using a heat storage fluorescent sheet, e.g., a digital radiographic system, CT, MR, etc., a wet system in which an image is photographed or recorded on a silver salt photographic light-sensitive material, and then wet processed to obtain a reproduced image has been used.
However, in recent years, a recording apparatus by a dry system in which wet processing is not necessary to be carried out has attracted public attention. In such a recording apparatus, a light-sensitive and/or a heat-sensitive recording material (a light-sensitive heat-sensitive recording material) and a heat-developable light-sensitive film (hereinafter referred to as "a recording material") are used. In this recording apparatus by a dry system, a latent image is formed by irradiation of a laser beam (scanning) on a recording material at an exposing part, then the recording material is heat developed by contacting with a heating means such as a heating drum at a heat developing part, thereafter the recording material on which an image has been formed is discharged from the recording apparatus.
By such a dry system, not only image formation can be effected within a short period of time as compared with wet processing but also a problem of the disposal of a waste solution in wet processing can be resolved, therefore, the increase of demand for such a system in the future is predictable enough.
In the above dry system, in general, a heating drum is used as a heating means, an endless belt is wound around the heating drum at a fixed angle, and heat development is carried out at a heat developing part with conveying the recording material holding between the heating drum and the endless belt. However, when the tensile force of the endless belt becomes uneven due to heat deterioration and the like, the recording material and the heating drum do not come into contact evenly, as a result, uneven development is generated.
In particular, as medical images are required to be high quality, recording materials are higher sensitive and even a slight unevenness of the contact state of the recording material with the heating drum largely deteriorates the image quality.
Further, in the heating means, the temperature lowering at the peripheral part where heat supply is low and the generation of folds and wrinkles by buckling at the end part of the heating means when a recording material is put between the heating drum and the endless belt become problems.
Further, as disclosed in Japanese Patent Application No. 9-229684, in the case of the first recording material (the dry silver light-sensitive material) described therein, there are anxieties of heat conduction failure between the recording material and the heater and contamination of the recording material, contamination of apparatus members, e.g., rollers, and corrosion of electronic parts due to the volatile material from the first recording material.